Threaded connections and methods for forming threaded connection

ABSTRACT

Systems related to threaded connections whereby off-center axial alignment of connected components is maintained. In one embodiment, threads on one connection component are timed to match the timing of the threads on the other connection component. The one component has a connection sleeve screwed thereon. Once the one component and the other component are mated in the desired axial alignment such that the threads on each joint form a continuous, unbroken thread, the connection sleeve is screwed onto the other component to form the threaded connection.

This application is the National Stage of International Application No.PCT/US04/021363, filed 2 Jul. 2004, which claims the benefit of U.S.Provisional Patent Application No. 60/503,043, filed 15 Sep. 2003.

FIELD OF THE INVENTION

This invention relates to the field of threaded connections and methodsfor forming threaded connections. More particularly, this inventionrelates to threaded connections and methods for forming same wherebyoff-center axial alignment of connected components is maintained.

BACKGROUND OF THE INVENTION

Typical oilfield connections rely on rotation to screw individualthreaded components together. The make-up of these relative rotationconnections requires that one or both components undergo rotationalmovement while the components are screwed together. This rotationalmovement does not prohibit axial alignment along the centerline of thecomponents during make-up, but it does prohibit axial alignment at anyoff-center location during the make-up process. This severely limits thenumber of separate ports/passages into the adjoining componentsavailable for wireline or hydraulic communication use. For example,consider the use of a relative rotation based threaded connectionbetween two components, each of which includes a wireline port thatpasses continuously therethrough at a location 2.54 cm (1 inch)off-center, and through which a wireline is disposed. During the make-upprocess, relative rotation between the two components causes thewireline ports to rotate in opposite directions along a circular pathrelative to each other, thus shearing the wireline. Although relativerotation type threaded connections provide high strength with minimaluse of a cylindrical cross-section, off-center axial alignment is notpossible during make-up.

Typical down-hole connections such as rotary shouldered connections,e.g., API numbered connections, AMERICAN MT, HUGHES H-90, and REED FULLHOLE, all of which are familiar to those skilled in the art, utilize apin and box connection requiring relative rotational movement.

Stab type pin and box connections which rely on some type of retainingpins or screws to hold the connection together, as is familiar to thoseskilled in the art, allow for a rotation free connection but lack thestrength needed for many down-hole applications, and take up much neededcross sectional area.

Connections are available that do not use relative rotation threadedconnections, and thus allow axial alignment during the connectionmake-up process. In these connections, axial alignment is typicallyenabled by using a collar that screws onto only one of the matingcomponents. The other mating component has a non-thread type connectionthat allows the collar to spin freely during the make-up process.Consequently, the non-threaded end requires a sub-optimal connectionthat necessarily requires a larger fraction of the availablecross-sectional area to provide the required strength. This limits theavailable cross-sectional area for non-connection related engineeringpurposes, and thus requires a larger diameter design to accommodate therequired engineering features, i.e., uses a large footprint design. Inmost cases a large footprint design dramatically decreases the utilityof the engineered component in down-hole applications, and in many casesrenders the component unusable.

A need exists for threaded connections that can be made-up whileoff-center alignment of connected components is maintained. An objectiveof this invention is to provide such threaded connections and methods ofmaking same.

SUMMARY OF THE INVENTION

The present invention pertains to threaded connections that allow formaintenance of off-center axial alignment during the make-up process. Abenefit of the present invention is that it preserves the inherentstrength of relative rotation based threaded type connections, as wellas the valuable low profile nature resulting from the characteristicannular geometry of engaged threads. As used in describing thisinvention, ports, passages, etc. that must extend from one componentinto one or more adjoining components for wireline or hydrauliccommunication use, for example, will be generally referred to as“openings”.

In one embodiment, a connection according to this invention comprisestwo components, each having one or more off-center openings that must bealigned to one or more openings in the other, and each having eitherexternal or internal threads machined onto one end. The timing is donein such a fashion that when the two components are axially aligned suchthat the one or more openings are aligned, and mated together, thethreads form a continuous unbroken thread across the junction betweenthe components. The physical connection between the two components isprovided by a threaded sleeve that initially screws onto one componentand then screws onto the other component after the components areaxially aligned and mated. When the connection is fully made-up, thesleeve's thread straddles the mating face between the components. Thisleaves approximately one-half of the sleeve's thread engaged onto theend of each of component.

The aspect of complete interchangeability of mating parts with asynchronized thread separates a connection according to this inventionfrom any other connection of which we are aware. In one embodiment, themachining processes utilized to make the components of a connectionaccording to this invention utilize a simple threaded master orientationcap and a master thread jig, which makes the synchronization processsimple and effective. The fabrication process involves timing referencepin locations on component 10 (FIG. 1) relative to the thread lead andthen adjusting the thread lead of the mating component 20 relative tothese reference pin locations. The reference pin locations arepredefined by the user and are machined into the body of the masterthread jig. These reference pin locations are placed onto component 10by threading the master orientation cap onto component 10, indicatingthe x-axis off of two alignment pins on the master orientation cap,transferring the reference pin locations onto the end of component 10,and then drilling reference holes at the predefined coordinates. Allmachining work on component 10 is done relative to these thread timingreference hole locations. This ensures that all ports and passages arepositioned at a known location relative to the part's thread lead. Thethreads of the mating part (component 20, FIG. 1) are timed relative tothe threads on component 10 through the use of a master thread jig. Thismaster jig is identical in appearance to component 10 and sleeve 30 ofFIG. 1, with two exceptions: (i) an access/viewing window has beenmilled into the side of sleeve 30 at an axial location that allowsaccess to the mating plane between parts 10 and 20; and (ii) referencepins have been placed at the proper location to ensure proper threadalignment with the thread timing created by the master orientation cap.The threads on component 20 are timed relative to component 10 by firstinstalling reference pin holes on the face of component 20 at thepredefined reference pin coordinates. These pin holes can be transferredfrom the other end of a part if the holes were previously generatedusing the master thread cap, or the pin holes can be independentlymachined. If the reference pin hole locations are independentlymachined, the pin holes are not placed in a location that is timedrelative to the thread lead. The pins in the master jig are theninserted into the reference holes in component 20 and the ends of thetwo parts are abutted together. The slotted collar is then screwed ontocomponent 20. If the threads between the master thread jig and component20 are not aligned then a gap will exist between the mating faces of themaster thread jig and component 20. The degree of misalignment isproportional to the gap between the two faces. The gap between the twoparts is then measured and the master thread jig is removed fromcomponent 20. Timing of the threads on component 20 is achieved byfacing off material from the end of the part to adjust the tangentiallocation where the thread lead starts relative to the reference pinlocations. The proper amount to face off is one thread pitch minus themeasured gap between the master thread jig and component 20. Uponcompletion of the facing operation, all machining on component 20 isperformed relative to the two reference hole locations. Also, the STUBACME thread form may be utilized, which greatly improves the resistanceto thread galling, and allows for greater misalignment when assemblingthe connection.

In another embodiment, a connection according to this inventioncomprises two components, each having one or more off-center openingsthat must be aligned to one or more openings in the other, and eachhaving either external or internal threads machined onto one end. Nospecial machining process is used to time the threads of one componentto the threads of the other component. The two components are alignedsuch that the one or more openings are aligned. If the two componentsare mated together such that the end of one abuts the end of another,the threads do not form a continuous, unbroken, thread. To form aconnection according to this invention, the aligned components areseparated by such a distance that if the threads on one component andthe threads on the other component were continuous through the distance,they would form a continuous-thread path between the two components. Theappropriate distance may be determined by one skilled in the art usingwell known techniques. A spacer that generates a separationsubstantially equal to the distance determined to be appropriate may beprovided between the aligned components to maintain the separation. Thespacer can be any suitable piece or device suitable for generating theseparation, as will be familiar to those skilled in the art. Examplespacers are shown in the drawings that illustrate this invention. Thephysical connection between the two components is created by a threadedsleeve that initially screws onto one component and then screws onto theother component after the components are axially aligned andappropriately spaced.

In one embodiment of this invention, a threaded connection forconnecting first and second substantially cylindrical-shaped componentshaving a pre-defined axial alignment comprises: A. (i) a first set ofthreads provided on a first component connection end of said firstcomponent, and (ii) a second set of threads provided on a secondcomponent connection end of said second component, (iii) such that whensaid first and second components are disposed in said pre-defined axialalignment and said first component connection end abuts said secondcomponent connection end, said first set of threads and said second setof threads are synchronous; and B. a connection collar adapted to be (i)threaded onto said first component connection end before said firstcomponent connection end abuts said second component connection end, and(ii) threaded onto said second component connection end, after saidsecond component connection end abuts said first component connectionend and said first and second components are disposed in saidpre-defined axial alignment, while said pre-defined axial alignment ismaintained. In one embodiment of this threaded connection, said firstset of threads is externally disposed on said first component connectionend and said second set of threads is externally disposed on said secondcomponent connection end. In another embodiment of this threadedconnection, said first set of threads is internally disposed on saidfirst component connection end and said second set of threads isinternally disposed on said second component connection end. In anotherembodiment of this threaded connection, said first component has one ormore openings therein that align with one or more openings in saidsecond component when said first and second components are disposed insaid pre-defined axial alignment. In another embodiment of this threadedconnection, an item is disposed through at least one of said openings insaid first component and through said aligned opening in said secondcomponent.

In one embodiment of this invention, a threaded connection forconnecting first and second substantially cylindrical-shaped componentshaving a pre-defined axial alignment comprises: A. (i) a first set ofthreads provided on a first component connection end of said firstcomponent, (ii) a second set of threads provided on a second componentconnection end of said second component, and (iii) said first and secondcomponents being disposed such that (i) said first component connectionend is separated from said second component connection end by such adistance that if said first set of threads and said second set ofthreads were continuous through said distance they would form acontinuous-thread path between said first component and said secondcomponent, and (ii) said first and second components are disposed insaid pre-defined axial alignment; and B. a connection collar adapted tobe (i) threaded onto said first component connection end before saidfirst component connection end is separated from said second componentconnection end by said distance, and (ii) threaded onto said secondcomponent connection end, after said first component connection end isseparated from said second component connection end by a distance andsaid first and second components are disposed in said pre-defined axialalignment, while said pre-defined axial alignment is maintained.

In another embodiment of this invention, a threaded connection forconnecting first and second substantially cylindrical-shaped componentshaving a pre-defined axial alignment comprises: A. a spacer having afirst spacer end and a second spacer end, B. (i) a first set of threadshaving a first timing and provided on a first component connection endof said first component, and (ii) a second set of threads having asecond timing and provided on a second component connection end of saidsecond component, (iii) such that when said first component connectionend abuts said first spacer end of said spacer and said second componentconnection end abuts said second spacer end of said spacer, when saidfirst and second components are disposed in said pre-defined axialalignment, said first set of threads and said second set of threads aresynchronous; and C. a connection collar adapted to be (i) threaded ontosaid first component connection end before said first componentconnection end abuts said first spacer end and said second spacer endabuts said second component connection end, and (ii) threaded onto saidsecond component connection end, after said second component connectionend abuts said second spacer end and said first spacer end abuts saidfirst component connection end and said first and second components aredisposed in said pre-defined axial alignment, while said pre-definedaxial alignment is maintained.

In another embodiment of this invention, a threaded connection forconnecting first and second substantially cylindrical-shaped componentshaving a pre-defined axial alignment comprises: A. a spacer having athreaded end and a top end, B. (i) a first set of threads having a firsttiming and provided on a first component connection end of said firstcomponent, and (ii) a second set of threads having a second timing andprovided on a second component connection end of said second component,(iii) such that when said first component connection end is attached tosaid threaded end of said spacer and said second component connectionend abuts said top end of said spacer, when said first and secondcomponents are disposed in said pre-defined axial alignment, said firstset of threads and said second set of threads are synchronous; and C. aconnection collar adapted to be (i) threaded onto said first componentconnection end before said first component connection end is attached tosaid threaded end of said spacer and said top end of said spacer abutssaid second component connection end, and (ii) threaded onto said secondcomponent connection end, after said second component connection endabuts said top end of said spacer and said threaded end of said spaceris attached to said first component connection end and said first andsecond components are disposed in said pre-defined axial alignment,while said pre-defined axial alignment is maintained.

DESCRIPTION OF THE DRAWINGS

The advantages of the present invention will be better understood byreferring to the following detailed description and the attacheddrawings in which:

FIG. 1 is an off-center cut-away view of one embodiment of a threadedconnection according to this invention.

FIG. 2 is an off-center cut-away view of one component used in makingthe threaded connection illustrated in FIG. 1.

FIG. 3 is an off-center cut-away view of another component used inmaking the threaded connection illustrated in FIG. 1.

FIG. 4 is a cut-away view of a connection collar used in making thethreaded connection illustrated in FIG. 1.

FIG. 5A is an off-center cut-away view of an embodiment of a threadedconnection according to this invention in which one or more spacers areutilized.

FIG. 5B illustrates one embodiment of a spacer that can be utilized inthis invention.

The same identifier is used throughout the drawings for any particularpart.

While the invention will be described in connection with its preferredembodiments, it will be understood that the invention is not limitedthereto. To the extent that the following description is specific to aparticular embodiment or a particular use of the invention, this isintended to be illustrative only, and is not to be construed as limitingthe scope of the invention. On the contrary, the invention is intendedto cover all alternatives, modifications, and equivalents which may beincluded within the spirit and scope of the present disclosure, asdefined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1-FIG. 4 illustrate one embodiment of this invention. In thisembodiment, first component 10 must be connected to second component 20in such a manner that the alignments of (i) opening 1 in first component10 with opening 2 in second component 20, and (ii) opening 3 in firstcomponent 10 with opening 4 in second component 20, are maintainedduring the connection make-up process. As shown, wireline 8 may beprovided through openings 1 and 2; and nipple 6 may be provided inopening 3 with nipple recipient 7 being provided in opening 4. Externalthreads are provided on connection ends abutting mating faces 14 and 24of components 10 and 20. The make-up process is initiated by threadingconnection sleeve 30 onto first component 10, preferably untilconnection sleeve end 34 abuts shoulder 16 of component 10. Secondcomponent 20 is then axially aligned with first component 10 such thatopening 2 is aligned with opening 1 and opening 3 is aligned withopening 4. In the embodiment shown in FIG. 1-FIG. 3, nipple 6 is alignedwith nipple recipient 7. With this alignment maintained, secondcomponent 20 is mated flush with first component 10 such that there isessentially no gap between mating face 24 and mating face 14. Connectionsleeve 30 is then threaded across the mating face onto second component20. Since the thread on component 10 is timed relative to the thread oncomponent 20, the thread path extending from component 10 is in-linewith component 20, and sleeve 30 follows a continuous thread across themating face. The high strength and low profile nature of the resultingconnection allows maximum use of the internal diameter of firstcomponent 10 and second component 20 for engineering purposes that mayor may not rely upon precise axial alignment. Additionally, firstcomponent 10 and second component 20 can be fabricated such that thereis essentially no external diameter upset (i.e., there is substantiallyconstant external diameter across the connection).

Threads 12 of first component 10, and threads 22 of second component 20,can be formed by various machining techniques that enable thesynchronization of the timing of the thread profiles. Sleeve 30 does notrequire any specialized machining processes because timing is notrequired. This fabrication process ensures that there is essentially nogap between mating face 14 of first component 10 and mating face 24 ofsecond component 20 after connection sleeve 30 is screwed into placed.As illustrated in FIGS. 1-5, but particularly FIG. 1, sleeve orconnection collar 30 includes an internal straight thread such that whenfirst component 10 is in pre-defined axial alignment with component 20,collar 30 threads continuously from the first component 10 onto thesecond component 20.

FIG. 5A illustrates another embodiment of this invention. In thisembodiment, mechanical synchronization of the timings of threads 12 andthreads 22 is not required. Instead, first component 10, havingconnection sleeve 30 already threaded thereon, and second component 20are placed in the proper axial alignment, i.e., such that any openingsthat need to be aligned, are aligned. For example, in the embodimentillustrated in FIG. 5A, opening 1 in first component 10 is aligned withopening 2 in second component 20 and opening 3 in first component 10 isaligned with opening 4 in second component 20. During the connectionmake-up process, first component 10 and second component 20 areseparated, while the alignment of openings 1 and 2 and of openings 3 and4 is maintained, until the distance between first component 10 andsecond component 20 (the “required distance”) is such that if threads 12and threads 22 were continuous through the required distance, they wouldform a continuous-thread path between first component 10 and secondcomponent 20. Proper alignment of the openings between component 10 andcomponent 20 can be provided using alignment pins, or nipples 6 andnipple recipients 7, that mate between the components, e.g., throughopenings 1 and 2 or through openings 3 and 4, as illustrated in FIGS.1-3. The required distance between first component 10 and secondcomponent 20 may be maintained by a spacer. For example, a spacer 26 maybe placed between components 10 and 20 such that a first end 26 a ofspacer 26 abuts mating face 14 of component 10 and a second end 26 b ofspacer 26 abuts mating face 24 of component 20. In this example, spacer26 is a suitable piece of metal, as will be familiar to those skilled inthe art. The spacer 26 may be sized to space the first and secondcomponents by a desired stand-off separation distance 28. In anotherembodiment, illustrated in FIG. 5B, a spacer 27 is adjustable and is inthe form of a screw. A threaded end 27 b of a spacer 27 is screwed intocomponent 20 via mating face 24 until the proper stand-off separationdistance 29 is achieved as shown, and a top end 27 a of spacer 27 abutsmating face 14 of component 10. In an alternative embodiment and asillustrated in FIG. 5B, an indention 24 a is provided in component 20 atmating face 24. In this embodiment, stand-off separation distance 29 ispreferably equal to the distance of one thread pitch or less. Once therequired distance is maintained, connection sleeve 30 is threaded fromfirst component 10 to second component 20. In yet another embodiment,the connection can be made up without a spacer by physically movingcomponent 20 axially away from component 10 until the required distanceis achieved and connection sleeve 30 is threaded from first component 10to second component 20 at least until the threads of sleeve 30 engagewith the threads on component 20. Other embodiments, either using aspacer or not, to generate the required distance are within the scope ofthis invention. Once the required distance is maintained, connectionsleeve 30 is threaded from first component 10 to second component 20.The required distance between mating faces 14 and 24 can range from zeroto several thread pitches. Any or all parts of a connection according tothis invention may be coated with a suitable coating to provideprotection from galling and/or corrosion, as will be familiar to thoseskilled in the art.

Unlike the connection type described earlier that relies upon anunthreaded free rotating collar, a connection according to thisinvention provides threads on both sides of the connection, thusenabling maximum use of the internal diameter, and maximum strength. Theinclusion of seals on each end of the connection enables the regioninternal to connection sleeve 30 to be pressure isolated from the regionexternal to connection sleeve 30; for example, see seals 5 in FIG. 1.Openings 1, 2, 3, and 4, e.g., may be used for numerous engineeringendeavors, for example, electrical plug type connections, nipples thatprovide sealed or unsealed fluid passage from one component to another,wireline passages, visualization passages for optical access, laser beamcommunication, ball or plug passage, or any other communication typethat requires, or can otherwise utilize, off-center alignment betweentwo mating components.

EXAMPLE

A full-scale model of a connection according to this invention wasconstructed to allow pressure testing of the required connection tensilestrength. A pressure of about 8.1 MPa (15 ksi) was applied to theinternal chamber of the connection which induced the required 486,000Newton's (109,000 lbs) tensile strength needed for the connection toperform in actual field conditions. Disassembly of the model showed nosigns of material deformation, or galling of the threads.

While the present invention has been described in terms of one or morepreferred embodiments, it is to be understood that other modificationsmay be made without departing from the scope of the invention, which isset forth in the claims below.

1. A threaded connection comprising: A. a spacer having a threaded endand a top end, B. (i) a first set of threads having a first timing andprovided on a first component connection end of a first component and(ii) a second set of threads having a second timing and provided on asecond component connection end of a second component, (iii) such thatwhen said second component connection end is attached to said threadedend of said spacer and said first component connection end abuts saidtop end of said spacer when said first and second components aredisposed in a pre-defined axial alignment, said first set of threads andsaid second set of threads are synchronous, and none of the first set ofthreads overlap with any of the second set of threads; and C. aconnection collar adapted to be (i) threaded onto said first componentconnection end, and (ii) threaded onto said second component connectionend after said first component connection end abuts said top end of saidspacer and said threaded end of said spacer is attached to said secondcomponent connection end and said first and second components aredisposed and maintained in pre-defined axial alignment while saidconnection collar is threaded onto said second component connection end.2. The threaded connection of claim 1 wherein said first set of threadsis externally disposed on said first component connection end and saidsecond set of threads is externally disposed on said second componentconnection end.
 3. The threaded connection of claim 1 wherein said firstcomponent has one or more openings therein that align with one or moreopenings in said second component when said first and second componentsare disposed in said pre-defined axial alignment.